Boring tool



E. DAVIS ROBIN@T001. y f- Filed Febi 4, 1925 1 I i A 4 w N N i 2.

M 7 m x Feb. 11, 1936;

Patented Feb. 11, 1930' nNITED STATES RM1-:Nr oFFica EMERY E. DAVIS, OFST. LOUIS, MISSORI, ASSIGNOR, BY MESNE ASSIGNMEN'SrTO DAVIS BORING TOOLCOMPANY, OF ST. LOUIS, MISSOURI, A CORPORATION OF MIS- SO'URI :BORINGTOOL Application filed February 4, 1925. lSerial No. 6,682.

rl`his invention pertains to boring tools and more particularly to thattype in which the cutter or cutters are adjustably mounted in a cutterblock which in turn is mounted in the boring bar.

In such a tool -especially where intendedY for very accurate work it isvery important that the cutters be accurately alined or centered in theboring bar. According to present constructions the cutter block isusually provided with a tapered hole or socket into which a taperedcentering plug may be set or centering the block in the boring bar. lnorder that the cutters may have a solid backing in the boring bar it isusual to set the centering plug slightly eccentrically with respect tothe socket in the block. The eccentricity is towards the rear of theboring bar so that the plug .when set in the socket will force the blockfirmly against the rear of the cutter block opening in the boring bar.With such a construction, even when the eccentricity is very slight, thecentering plug has a bearing against thevblock practical-ly along asingle line only. rlhis line is furthermore not accurately determinedsince it forms the contact of one cone within another'of substantiallythe same size. In fact the bearing line may change with successivesettings of the block.` Accordingly precise centering of the cutterblock is impossible with such a construction.

@ne of the objects of this invention, therefore, is to provide aconstruction in which the centering plug will accurately center thecutter block in the boring bar. o Another object is to provide improvedmeans for adjusting the cutter in the block.

Anohter object is to provide improved means `for clamping the cutters inadjusted position.

Further objects will appear from the following description. taken inconnection with the accompanying drawing in which: h

Figure l is a top view of a cutter block embodying this invention; i

Figure 2 is afront view of same shown with the adjusting wrench inplace;

Figure 3 is a central longitudinal section of part of the boring bartaken transversely of the cutter Fig. 4 is a section on line 4--4 ofFigure 3;

Figure 5 is a detail section on line 5 5 of Figure 2; and

Figure 6 is an enlarged detail of Figure 4 showing the engagement of thecentering plug with its socket.

Referring now to the drawing 1 designates the body of the cutter block.'llhis may be provided with 1 or more grooves or channels 2 in which thecutters 3 are mounted for sliding adjustment. rlFhe grooves 2 may be cutat an angle with the axis of the block and the cutters may be adjustedtherein by sliding them forwardly and outwardly for increasing thediameter of the bore cut. rlhe rear end of the cutter 3 may be taperedso as to provide an angularly disposed abutment 4.,

- Mounted in the block l but at an inclination with the cutter 3 is anadjusting screw 5 provided with a flat end forming an abutment adaptedto engage the abutment 4 of the cutter. By screwing up the screw 5 thecutter 3 will be fed forwardly along its slot so as to increase th-ediameter of the bore cut.l The head of the vscrew 5 may be provided withan angular socket 6 adapted to reecive the correspondingly formed head 7of a wrench 8 for adjusting the same. rllhe wrench 8 may be providedwith a flange 9 provided with a suitable scale which, in co-operationwith an index 10, is adapted to indicate the' exact amount of adjustmentof the cutter 3. Byo

desired ade accurately means of this construction an justment of thecutter may made by referring to the scale 9. n

` The cutter 3 may be clamped in adjusted position by one or moreclamping elements '11 each fitting in a tapered socket 12 in the gagingthe side face of the cutter 3 for clamping the same in place. The socket12 is Jform-ed to fit the element 11 so that there will be no tendencyof the clamping element to turn round in itssocket when the cutter 3 hastime be withdrawn, for repairs or replace- `ment by a new cutter, andwhen the cutter is inserted the clamping elements will always be in theproper position to enga e the same.

In order to provide for accurate y centering the cutters in the boringbar a centering socket is rovided in the block 1. This socket is reerably placed in the axis of the block as etermined by the grindingcenters 16, but may of course, be placed in any other suitable osition.In a direction from the center o Vthe socket 15 parallel to the axis ofthe block a V-notch 17 is cut in the socket and preferabl parallel tothe side thereof. The notch 17 as its sides accurately located at equaldistances from the axis through the center of the socket." The boringbar 18 may have mounted therein a centering plug having a taperedportion 19, a screw head 20 and a pilot 21. The head 20 engages threadsin the oring bar while the pilot 21 engages a suitable pilot holetherein. The axis of the centering plu is slightly nearer to the rearface 22 of the lockopening in the boring bar than is thecenter of thesocket 15 in the block. This provides that when the plug is screwed downit will force the block rearwardly against the face 22. In so doing theplug 19 engages the socket 15, not along a single line as in theordinary construction, but along two bearing parts formed at the edges23 of the notch or roove 17 as illustrated in Figuure 6. In this figurethe eccentricity is of course greatly exaggerated `but the ligure showsthat the plug beais against the socket at the two bearing points 23which are equally spaced on opposite sides of the centering axis 24passing through the center of the socket 15. This provision of twobearing parts on opposite sides of the centering axis insures that theplug will always bear at these two points and eliminates lentirely thepossibility of bearing at .a single point or line which may shift itsposition from time to time.

It`will thus be seen that in accordance with i this invention the cutterblock may beacourately centered in the boring bar so that when thecutters have been adjusted and accurately` ground on the centers 16, itmay be mounted `the adjusting screws-5 provides a solid bearing betweenflat surfaces at the abutment 4 so as to avoid excessive wear at thispoint, while at the same time, the screw 5 is set in the block at suchanangle as to make it convenient to use the'wrench 8 for adjusting theysame so that the adjustment may be observed on the indicating scale ,9.The improved construction of the clamping elements 11 alsoavoidsinconvenience in removing and replacing cutters -since the clampingelements will retain their the cutter.

It is,obvious that various changes may be made in the details ofconstruction without position facing "departing from the spirit of thisinvention;

it is to be understood, therefore, that this invention is not to belimited to the specific details shown and described.

Having thus described the invention what is claimed is:

1. In a boring tool,A a block provided with a centering socket having acentering groove providing clearly defined bearing parts on oppositesides of and positioned laterally of a centering axis, and a centeringplug in said axis engaging said socket and forced against and betweensaid parts so as to bear equally on said parts.

2. In a boring tool of the type in which a cutter block is mounted inaboring bar, means for centering the block, comprising, means on vtheblock providing a centering socket adapted to receive a centering plug,the walls of said socket having a gap providing at its edges clearlydefined spaced bearing parts, a plug adapted lto enter said socket toengage said bearing parts, and means for forcing said plug against andbetween said parts in order to center the block.

v3. In a boring tool, a cutter block, a pair of cutters mounted foradjustment therein in inclined directions relatively thereto andlaterally spacedfrom one another, each of said cutters having anabutment at the end thereof inclined to said cutter so as to approachparallelism with the rear face of said lock, an adjusting screw for eachof said cutters movable in a direction nearly perpendicular to the rearface of said block and engaging said abutment perpendicularly to adjustsaid-cutter, said block having a truing center between said screws, andmeans for -manipulating said screws havin a graduated dial elementmovable vtherewit in a plane approaching parallelism with said rear faceof said block and co-operating with an index thereon to indicate theextent of adjustment.

4. In a boring tool, a cutter block, a pair of cutters mounted foradjustment therein in inclined directions relatively thereto andlaterally spaced from one another, each of said cutters having anabutment at the end thereof inclined to said cutter so as to approachparallelism with the rear face of said block, an adjustingpscrew foreach of said cutters movable in a direction nearly perpendicular to therear face of said block and engaging said abutment perpendicularly toadjust said cutter, and means for manipulating said screws having agraduated dial element movable therewith in a plane approachingparallelism with said rear face of said block and cooperating with anindex thereon to indicate the extent o f adjustment, said block having ecentering element on said rear face between said. screws.

In testimony whereof I aix my signature this 19th day of Dec., 1924.

